A liquid crystal display device in which a liquid crystal composition is used is widely used for a display of a watch, a calculator, a cellular phone, a personal computer, a television receiver and so forth. The liquid crystal display devices utilize refractive index anisotropy or dielectric anisotropy of a liquid crystal compound, or the like. As an operating mode of the liquid crystal display device, a twisted nematic (TN) mode, a super twisted nematic (STN) mode, a bistable twisted nematic (BTN) mode, an electrically controlled birefringence (ECB) mode, an optically compensated bend (OCB) mode, an in-plane switching (IPS) mode, a vertical alignment (VA) mode or the like is known, in which one or more polarizing plates are mainly used. Further, a research has been recently conducted into a mode in which an electric field is applied thereto in an optically isotropic liquid crystal phase to develop electric birefringence (Patent literature Nos. 1 to 15, Non-patent literature Nos. 1 to 3).
Further, a proposal has been made on a wavelength variable filter, a wavefront control device, a liquid crystal lens, an aberration correction device, an aperture control device, an optical head device or the like utilizing electric birefringence in a blue phase being one of optically isotropic liquid crystal phases (Patent literature Nos. 10 to 12).
A classification based on a driving mode in the device includes a passive matrix (PM) and an active matrix (AM). The passive matrix (PM) is classified into static, multiplex and so forth, and the AM is classified into a thin film transistor (TFT), a metal insulator metal (MIM) and so forth according to a kind of a switching device thereof.
As a liquid crystal composition used for a liquid crystal display device, Patent literature No. 14 includes an example of reporting an optically isotropic liquid crystal composition containing a compound having two biphenyl groups and a difluoromethoxy linking group. However, although the liquid crystal composition disclosed in Patent literature No. 14 exhibits a large dielectric anisotropy and is effective in reducing a drive voltage of a display, the composition has had an issue of a large temperature dependence of the drive voltage in a temperature range centering on an operating temperature.
Compound (1) of the present application has features of having two biphenyl groups and a difluoromethoxy linking group, and an optically isotropic liquid crystal composition containing compound (1) of the present application has features of small temperature dependence of the drive voltage in the temperature range centering on the operating temperature. No description of the temperature dependence of drive voltage is found in Patent literature No. 14. An effect of minimizing the temperature dependence of the drive voltage is a finding that has been found out for the first time according to the instant invention.